A method for preparing self-repairing mortar by using active cement particle microcapsules

Abstract

This invention provides a method for preparing self-healing mortar using microcapsules of active cement particles, comprising: (1) preparation and microencapsulation of active cement particles: after uniformly mixing the components in proportion, pressing and drying, adsorbing PEG, crushing, and spraying m-phenylenediamine on the surface of the particles to obtain active cement particles, and preparing microcapsules by encapsulating the active cement particles with polymer through a combination of interfacial polymerization and melt cooling; (2) preparing self-healing mortar using the prepared microcapsules of active cement particles, cracking and testing the self-healing effect. The innovations of this invention are: (1) preparing active cement particle core material and using polymer to encapsulate the solid core material to prepare microcapsules; (2) the microcapsules can rupture and release self-healing substances in the self-healing mortar, and the self-healing mortar prepared using microcapsules of active cement particles has obvious self-healing effect, and has obvious repair effect on microcracks with a width of less than 287.3±22.7μm.

Description

Technical Field

[0001] This invention relates to a method for preparing self-healing mortar using microcapsules of active cement particles. The method involves preparing microcapsules by encapsulating active cement particles with polymers, and then adding the prepared microcapsules to the mortar to produce a self-healing mortar capable of self-healing cracks. Background Technology

[0002] Cement-based materials are widely used building materials due to their ability to meet various requirements in practical engineering projects. However, during use, under the combined effects of external loads and uneven shrinkage, microcracks inevitably form within cement-based materials. These microcracks accelerate the erosion of the matrix by external corrosive substances, ultimately leading to serious durability problems. Therefore, how to effectively repair microcracks in cement-based materials is a problem that must be solved in the engineering field.

[0003] Traditional repair techniques require significant manpower and resources, lack real-time monitoring capabilities, and have limited repair depth. Self-healing technology in cement-based materials can automatically repair cracks in cement-based matrices, and many scientists have conducted various studies on self-healing cement-based materials. This technology uses microcrack propagation and ultraviolet light as stimuli, utilizing self-healing substances embedded in the matrix to fill and bond the matrix, thus achieving automatic repair of the cement-based material.

[0004] Microcapsule self-healing technology, as a type of self-healing technology for cement-based materials, has been widely studied by numerous scholars due to its ease of preparation, large-scale production, and certain self-healing effects. However, currently, most microcapsules use liquid self-healing agents as the core, resulting in low microcapsule strength. These microcapsules are prone to breakage during mixing with cement slurry, negatively impacting the strength and porosity of the cement matrix. Some solid core microcapsules also suffer from weak self-healing effects and imperfect preparation processes. To address these issues, we use activated cement particles as the core and polymers as the outer shell to prepare activated cement particle microcapsules. When microcracks propagate and cause the microcapsules to crack, the activated cement particles in the core expand and harden based on different mechanisms, thereby achieving adhesion and sealing of the microcracks, thus realizing self-healing of the cement-based material. Microcapsules using activated cement particles as the core effectively solve problems such as low strength of liquid core materials, weak self-healing effects of some solid core materials, and poor interface filling and adhesion. They can be applied to mortars, further expanding the application areas and uses of self-healing cement-based materials.

[0005] Patent CN116514435A (publication date: August 1, 2023) describes the preparation of small-particle microcapsules by encapsulating styrene-acrylic emulsion with polyethylene terephthalate (PET), which has a high melting point. These microcapsules and the styrene-acrylic emulsion are then encapsulated with a low-melting-point mineral wax / beeswax composite wall material to form a microcapsule assembly. Adding this styrene-acrylic emulsion microcapsule assembly to concrete yields a self-healing cementitious material. When cracks appear in the concrete, the stress at the microcapsule tips breaks down the microcapsule walls, allowing the styrene-acrylic emulsion to diffuse into the cracks. Due to its multi-layered structure, it can achieve multiple self-repairs of the concrete cracks. While microcapsules with a liquid core material can also effectively repair microcracks, the microcapsules themselves have low strength, significantly impacting the strength of the concrete matrix.

[0006] Patent CN115536329B (publication date: December 30, 2022) describes a method for preparing self-healing granules by placing sodium carbonate, silica fume, silica, quicklime, magnesium oxide, an expanding agent, and bentonite into a disc granulator. The inner core is then coated with epoxy resin to create a water-blocking layer. The epoxy-coated granules are spread into cement powder, forming an outer protective shell. The mixture is then sieved to obtain the final self-healing granules. These granules are mixed with cement and quartz sand to prepare self-healing mortar. When cracks appear in the mortar, the stress at the tips destroys the self-healing granules, and the internal repair agent dissolves in water to generate a repair substance that fills the microcracks. While the self-healing granules prepared in this patent can effectively heal microcracks in the matrix, the relatively large size of the granules is not conducive to practical application, and the granulation process itself hinders large-scale production.

[0007] Patent CN114716177B (publication date: July 8, 2022) describes a process where cement particles, paraffin wax, isocyanate, n-hexane, and an emulsifier are mixed to form an oil phase, which is then dispersed in an aqueous phase (with an anionic surfactant added). Through emulsification, interfacial polymerization, and condensation, microcapsules with cement particles as the core material are obtained. The prepared microcapsules exhibit good dispersibility. This patent describes microcapsules with a solid core material, aiming to achieve homogeneous repair through cement repair. However, the prepared microcapsule walls are porous, resulting in low rupture efficiency during application, and the internal cement core material has low activity, leading to unsatisfactory self-healing effects.

[0008] Current patents primarily focus on encapsulating liquid repair agents, with a few encapsulating solid repair materials, enabling the preparation of microcapsules using solid particles as the core material. However, the core of liquid repair agent microcapsules is an organic repair agent, making it impossible to apply solid particles or cement particles to self-healing cement-based materials, or resulting in weak self-healing effects. Encapsulating active cement particles to prepare microcapsules can solve problems such as low microcapsule strength and poor compatibility between self-healing products and the matrix. Self-healing mortar prepared using active cement particle microcapsules can effectively heal microcracks generated in the matrix, but there have been no related reports domestically or internationally. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides an active cement particle microcapsule and a method for preparing self-healing mortar using the active cement particle microcapsule. This invention is based on the principle that after the microcapsule ruptures, the core material inside comes into contact with and reacts with water, causing the self-healing product to expand and bond to the ruptured cement matrix, thereby repairing various properties of the cement mortar.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing and encapsulating activated cement particles, comprising: mixing activated cement powder and PVP ethanol solution; compacting the mixture using a press, followed by crushing and drying; placing activated cement blocks in liquid organic matter and applying a vacuum to allow the liquid organic matter to be adsorbed inside the activated cement blocks; crushing the activated cement blocks with adsorbed organic matter into small particles; spraying m-phenylenediamine-ethanol solution onto the surface of the small particles; and drying to obtain the final activated cement particles; and encapsulating the activated cement particles with a polymer (mainly a mixture of tristearate glycerol and isocyanate) using a combination of interfacial polymerization and melt condensation to prepare activated cement particle microcapsules.

[0012] The active cement powder in step (1) is prepared according to the mass ratio, with each part of active cement powder being 150.0g, wherein the mass ratio of cement to expansive agent is between 9:1 and 6:4, and the amount of retarder added is between 0.15g and 4.5g.

[0013] The cement used in the preparation of activated cement particles is ordinary Portland cement; the expanding agent is bentonite or UEA concrete expanding agent (Wuhan Ounce Manpen Building Materials Co., Ltd.); the retarder is one or more of sodium tripolyphosphate, citric acid, sodium gluconate, and boric acid; the concentration of PVP ethanol solution is 5.0wt%-50.0wt%, and the amount added is 0.6g-60.0g depending on the solution concentration; the adsorbed organic matter is one or more of PEG, paraffin, and m-phenylenediamine with different molecular weights; the particle size of the crushed cement particles is between 100μm and 1250μm.

[0014] Secondly, the present invention provides a method for preparing self-healing mortar using active cement particle microcapsules, which involves fully mixing microcapsules, cement, sand and water in different proportions.

[0015] Compared with existing technologies, this invention successfully encapsulates active cement particles, and the resulting microcapsules have significantly higher strength than those with liquid core materials, as well as good dispersibility and crack sensitivity. The self-healing mortar prepared using active cement particle microcapsules exhibits obvious self-healing phenomena in a humid and water-rich environment after cracks are generated, and the water resistance of the repaired samples is restored. Attached Figure Description

[0016] Figure 1 a is a microscopic image of the prepared microcapsules; Figure 1 b is a cross-sectional view of the obtained microcapsules; Figure 1 c is a diagram showing the self-healing effect of the cement mortar sample without microcapsules; Figure 1 d is a diagram showing the self-healing effect of the cement mortar sample with 20.0 wt% microcapsules in Example 4. Figure 1 e represents the relationship between the outflow volume and the outflow time of 5g of water during the complete outflow of water through the crack after the control sample, Example 1, Example 2, and Example 4 samples were repaired. Detailed Implementation

[0017] Example 1

[0018] A method for preparing self-healing mortar, comprising the following:

[0019] Step 1: Preparation of self-healing particles and microcapsules, the process is as follows:

[0020] 120.0g of cement (PC 42.5), 30.0g of bentonite, 0.9g of sodium tripolyphosphate, and 15.0g of PVP ethanol solution (20.0wt%) were uniformly mixed and pressed into shape under a pressure of 200.0kN. After adsorbing PEG2000, the mixture was crushed and screened to obtain active cement particles with a particle size of 600-900μm. A 25.0wt% m-phenylenediamine-ethanol solution was sprayed onto the surface of the active cement particles, and the particles were dried to obtain the final active cement particles.

[0021] 10.0g of activated cement particles, 12.0g of tristearate, 7.2g of IPDI, 0.8g of Suprasec 2644, 0.75g of Span 85 and 0.75g of toluene were uniformly mixed as the oil phase and heated to 75°C in a water bath. 9.0g of SDBS and 3.0g of TEPA were dissolved in 600mL of water and heated to 75°C in a water bath. The oil phase was then poured into the aqueous phase to uniformly disperse the particles, thus preparing activated cement particle microcapsules.

[0022] Step 2: Preparation of self-healing cement mortar:

[0023] Weigh 225g of water, 450g of cement, 22.5g of microcapsules, and 1350g of sand, and add them to a mixing pot in the order weighed, then mix thoroughly. Pour the thoroughly mixed slurry into a mold, and demold after standard curing for 24 hours. The sample is then cured in water for 7 days. To test the self-healing effect of the self-healing mortar, 0.5wt% PVA fiber was added to the mortar to control cracking. A splitting crack test was performed on the cured sample to pre-create microcracks. The cracked sample was then immersed in water to undergo the self-healing process, and the self-healing effect was observed under a microscope after 7 days.

[0024] The self-healing mortar prepared using active cement particle microcapsules has good fluidity, high strength after setting and hardening, and a certain self-healing effect. It has a significant healing effect on microcracks smaller than 80μm and delays the complete passage of 5.0g of water through the crack by 30 seconds.

[0025] Example 2

[0026] A method for preparing self-healing mortar, comprising the following:

[0027] Step 1: Preparation of self-healing particles and microcapsules, the process is as follows:

[0028] 120.0g of cement (PC 42.5), 30.0g of bentonite, 0.9g of sodium tripolyphosphate, and 15.0g of PVP ethanol solution (20.0wt%) were uniformly mixed and pressed into shape under a pressure of 200.0kN. After adsorbing PEG2000, the mixture was crushed and screened to obtain active cement particles with a particle size of 600-900μm. A 25.0wt% m-phenylenediamine-ethanol solution was sprayed onto the surface of the active cement particles, and the particles were dried to obtain the final active cement particles.

[0029] 10.0g of activated cement particles, 10.0g of tristearate, 9.0g of IPDI, 1.0g of Suprasec 2644, 0.25g of Span 85 and 0.25g of toluene were uniformly mixed as the oil phase and heated to 65°C in a water bath. 3.0g of SDBS and 1.0g of TEPA were dissolved in 400mL of water and heated to 65°C in a water bath. The oil phase was then poured into the aqueous phase to uniformly disperse the particles, thus preparing activated cement particle microcapsules.

[0030] Step 2: Preparation of self-healing cement mortar:

[0031] Weigh 225g of water, 450g of cement, 45.0g of microcapsules, and 1350g of sand, and add them to a mixing pot in the order of weighing. Mix thoroughly. Pour the fully mixed slurry into a mold, and demold after standard curing for 24 hours. The sample is then cured in water for 7 days. To test the self-healing effect of the self-healing mortar, 0.5wt% PVA fiber was added to the mortar to control cracks. A splitting crack test was performed on the cured sample to pre-create microcracks. Water was dripped onto the cracks to keep the inside of the cracks moist and water-rich. The self-healing effect was observed under a microscope after 3 days.

[0032] The self-healing mortar prepared using active cement particle microcapsules has good fluidity, high strength after setting and hardening, and a certain self-healing effect. It has a significant healing effect on microcracks smaller than 100μm and delays the complete passage of 5.0g of water through the crack by 90 seconds.

[0033] Example 3

[0034] A method for preparing self-healing mortar, comprising the following:

[0035] Step 1: Preparation of self-healing particles and microcapsules, the process is as follows:

[0036] 135.0g of cement (PC 42.5), 15.0g of bentonite, 0.6g of citric acid and 15.0g of PVP ethanol solution (10.0wt%) were uniformly mixed and pressed into shape under a pressure of 200.0kN. After adsorbing PEG2000, the mixture was crushed and screened to obtain active cement particles with a particle size of 600-900μm. A 25.0wt% m-phenylenediamine-ethanol solution was sprayed onto the surface of the active cement particles, and the particles were dried to obtain the final active cement particles.

[0037] 10.0g of activated cement particles, 12.0g of tristearate, 7.2g of IPDI, 0.8g of Suprasec 2644, 0.5g of Span 85 and 0.5g of toluene were uniformly mixed as the oil phase and heated to 65°C in a water bath. 1.0g of SDBS and 1.0g of TEPA were dissolved in 400mL of water and heated to 65°C in a water bath. The oil phase was then poured into the aqueous phase to uniformly disperse the particles, thus preparing activated cement particle microcapsules.

[0038] Step 2: Preparation of self-healing cement mortar:

[0039] Weigh 270g of water, 450g of cement, 67.5g of microcapsules, and 1350g of sand, and add them to a mixing pot in the order of weighing. Mix thoroughly. Pour the well-mixed slurry into molds, and demold after standard curing for 24 hours. The samples are then cured in water for 28 days. To test the self-healing effect of the self-healing mortar, 0.5wt% PVA fiber was added to the mortar to control cracks. A splitting crack test was performed on the cured samples to pre-create microcracks. Water was dripped onto the cracks to keep the inside of the cracks moist and water-rich. The self-healing effect was observed under a microscope after 7 days.

[0040] The self-healing mortar prepared using active cement particle microcapsules has good fluidity, high strength after setting and hardening, and a certain self-healing effect. It has a significant healing effect on microcracks smaller than 150μm and delays the complete passage of 5.0g of water through the crack by 120 seconds.

[0041] Example 4

[0042] A method for preparing self-healing mortar, comprising the following:

[0043] Step 1: Preparation of self-healing particles and microcapsules, the process is as follows:

[0044] 120.0g of cement (PC 42.5), 30.0g of bentonite, 0.9g of sodium tripolyphosphate, and 15.0g of PVP ethanol solution (20.0wt%) were uniformly mixed and pressed into shape under a pressure of 200.0kN. After adsorbing PEG2000, the mixture was crushed and screened to obtain active cement particles with a particle size of 600-900μm. A 25.0wt% m-phenylenediamine-ethanol solution was sprayed onto the surface of the active cement particles, and the particles were dried to obtain the final active cement particles.

[0045] 10.0g of activated cement particles, 12.0g of tristearate, 7.2g of IPDI, 0.8g of Suprasec 2644, 0.75g of Span 85 and 0.75g of toluene were uniformly mixed as the oil phase and heated to 75°C in a water bath. 9.0g of SDBS and 3.0g of TEPA were dissolved in 600mL of water and heated to 75°C in a water bath. The oil phase was then poured into the aqueous phase to uniformly disperse the particles, thus preparing activated cement particle microcapsules.

[0046] Step 2: Preparation of self-healing cement mortar:

[0047] Weigh 225.0g of water, 450.0g of cement, 90.0g of microcapsules, and 1350.0g of sand, and add them to a mixing pot in the order of weighing. Mix thoroughly. Pour the well-mixed slurry into molds, and demold after 24 hours of standard curing. The samples are then cured in water for 28 days. To test the self-healing effect of the self-healing mortar, 0.5wt% PVA fiber was added to the mortar to control cracking. A splitting crack test was performed on the cured samples to pre-create microcracks. The cracked samples were then immersed in water to undergo the self-healing process. The self-healing effect was observed under a microscope after 7 days.

[0048] The self-healing mortar prepared using active cement particle microcapsules has good fluidity, high strength after setting and hardening, and a certain self-healing effect. It has a significant healing effect on microcracks below 287.3±22.7μm and delays the complete passage of 5.0g of water through the crack by 270 seconds.

[0049] Example 5

[0050] A method for preparing self-healing mortar, comprising the following:

[0051] Step 1: Preparation of self-healing particles and microcapsules, the process is as follows:

[0052] 120.0g of cement (PC 42.5), 30.0g of UEA concrete expansion agent (Wuhan Ounce Manpen Building Materials Co., Ltd.), 0.9g of citric acid, and 10.0g of PVP ethanol solution (30.0wt%) were uniformly mixed and pressed into shape under a pressure of 200.0kN. After adsorbing PEG4000, the mixture was crushed and screened to obtain active cement particles with a particle size of 300-900μm. A 25.0wt% m-phenylenediamine-ethanol solution was sprayed onto the surface of the active cement particles, and the particles were dried to obtain the final active cement particles.

[0053] 10.0g of activated cement particles, 12.0g of tristearate, 7.2g of IPDI, 0.8g of Suprasec 2644, 0.75g of Span 85 and 0.75g of toluene were uniformly mixed as the oil phase and heated to 75°C in a water bath. 9.0g of SDBS and 3.0g of TEPA were dissolved in 600mL of water and heated to 75°C in a water bath. The oil phase was then poured into the aqueous phase to uniformly disperse the particles, thus preparing activated cement particle microcapsules.

[0054] Step 2: Preparation of self-healing cement mortar:

[0055] Weigh 225g of water, 450g of cement, 67.5g of microcapsules, and 1350g of sand, and add them to a mixing pot in the order of weighing. Mix thoroughly. Pour the fully mixed slurry into molds, and demold after standard curing for 24 hours. The samples are then cured in water for 14 days. To test the self-healing effect of the self-healing mortar, 0.5wt% PVA fiber was added to the mortar to control cracking. A splitting crack test was performed on the cured samples to pre-create microcracks. The cracked samples were then immersed in water to undergo the self-healing process, and the self-healing effect was observed under a microscope after 7 days.

[0056] The self-healing mortar prepared using active cement particle microcapsules has good fluidity, high strength after setting and hardening, and a certain self-healing effect. It has a significant healing effect on microcracks smaller than 100μm and delays the complete passage of 5.0g of water through the crack by 100 seconds.

[0057] Example 6

[0058] A method for preparing self-healing mortar, comprising the following:

[0059] Step 1: Preparation of self-healing particles and microcapsules, the process is as follows:

[0060] 105.0g of cement (PC 42.5), 45.0g of UEA concrete expansion agent (Wuhan Ounce Manpen Building Materials Co., Ltd.), 0.6g of sodium gluconate, and 12.0g of PVP ethanol solution (25.0wt%) were uniformly mixed and pressed into shape under a pressure of 200.0kN. After adsorbing PEG6000, the mixture was crushed and screened to obtain active cement particles with a particle size of 600-1200μm. A 25.0wt% m-phenylenediamine-ethanol solution was sprayed onto the surface of the active cement particles, and the particles were dried to obtain the final active cement particles.

[0061] 10.0g of activated cement particles, 10.0g of tristearate, 9.0g of IPDI, 1.0g of Suprasec 2644, 0.5g of Span 85 and 0.5g of toluene were uniformly mixed as the oil phase and heated to 65°C in a water bath. 9.0g of SDBS and 3.0g of TEPA were dissolved in 600mL of water and heated to 65°C in a water bath. The oil phase was then poured into the aqueous phase to uniformly disperse the particles, thus preparing activated cement particle microcapsules.

[0062] Step 2: Preparation of self-healing cement mortar:

[0063] Weigh 180g of water, 450g of cement, 67.5g of microcapsules, and 1350g of sand, and add them to a mixing pot in the order of weighing. Mix thoroughly. Pour the fully mixed slurry into molds, and demold after standard curing for 24 hours. The samples are then cured in water for 28 days. To test the self-healing effect of the self-healing mortar, 0.5wt% PVA fiber was added to the mortar to control cracking. A splitting crack test was performed on the cured samples to pre-create microcracks. The cracked samples were then immersed in water to undergo the self-healing process, and the self-healing effect was observed under a microscope after 7 days.

[0064] The self-healing mortar prepared using active cement particle microcapsules has good fluidity, high strength after setting and hardening, and a certain self-healing effect. It has a significant healing effect on microcracks smaller than 150μm and delays the complete passage of 5.0g of water through the crack by 90 seconds.

[0065] Example 7

[0066] A method for preparing self-healing mortar, comprising the following:

[0067] Step 1: Preparation of self-healing particles and microcapsules, the process is as follows:

[0068] 120.0g of cement (PC 42.5), 30.0g of UEA concrete expansion agent (Wuhan Ounce Manpen Building Materials Co., Ltd.), 0.9g of citric acid, and 30.0g of PVP ethanol solution (10.0wt%) were uniformly mixed and pressed into shape under a pressure of 200.0kN. After adsorbing PEG4000, the mixture was crushed and screened to obtain active cement particles with a particle size of 300-600μm. A 25.0wt% m-phenylenediamine-ethanol solution was sprayed onto the surface of the active cement particles, and the particles were dried to obtain the final active cement particles.

[0069] 10.0g of activated cement particles, 8.0g of tristearate, 10.8g of IPDI, 1.2g of Suprasec 2644, and 0.75g of Span 85 were uniformly mixed to form the oil phase and heated to 65°C in a water bath. 9.0g of SDBS and 3.0g of TEPA were dissolved in 600mL of water and heated to 65°C in a water bath. The oil phase was then poured into the aqueous phase to uniformly disperse the particles, thus preparing activated cement particle microcapsules.

[0070] Step 2: Preparation of self-healing cement mortar:

[0071] Weigh 135g of water, 450g of cement, 45.0g of microcapsules, and 450g of sand, and add them to a mixing pot in the order of weighing. Mix thoroughly. Pour the fully mixed slurry into a mold, and demold after standard curing for 24 hours. The sample is then cured in water for 7 days. To test the self-healing effect of the self-healing mortar, 0.5wt% PVA fiber was added to the mortar to control cracks. A splitting crack test was performed on the cured sample to pre-create microcracks. Water was dripped onto the cracks to keep the inside of the cracks moist and water-rich. The self-healing effect was observed under a microscope after 7 days.

[0072] The self-healing mortar prepared using active cement particle microcapsules has good fluidity, high strength after setting and hardening, and a certain self-healing effect. It has a significant healing effect on microcracks smaller than 100μm and delays the complete passage of 5.0g of water through the crack by 60 seconds.

[0073] Example 8

[0074] A method for preparing self-healing mortar, comprising the following:

[0075] Step 1: Preparation of self-healing particles and microcapsules, the process is as follows:

[0076] 120.0g of cement (PC 42.5), 30.0g of bentonite, 0.9g of boric acid and 10.0g of PVP ethanol solution (30.0wt%) were uniformly mixed and pressed into shape under a pressure of 200.0kN. After adsorbing PEG4000, the mixture was crushed and screened to obtain active cement particles with a particle size of 900-1200μm. A 25.0wt% m-phenylenediamine-ethanol solution was sprayed onto the surface of the active cement particles, and the particles were dried to obtain the final active cement particles.

[0077] 10.0g of activated cement particles, 8.0g of tristearate, 10.8g of IPDI, 1.2g of Suprasec 2644, and 0.75g of Span 85 were uniformly mixed to form the oil phase and heated to 65°C in a water bath. 9.0g of SDBS and 3.0g of TEPA were dissolved in 600mL of water and heated to 65°C in a water bath. The oil phase was then poured into the aqueous phase to uniformly disperse the particles, thus preparing activated cement particle microcapsules.

[0078] Step 2: Preparation of self-healing cement mortar:

[0079] Weigh 135g of water, 450g of cement, 1350g of sand, and 135.0g of microcapsules, and add them to a mixing pot in the order of weighing. Mix thoroughly. Pour the fully mixed slurry into a mold, and demold after standard curing for 24 hours. The sample is then cured in water for 7 days. To test the self-healing effect of the self-healing mortar, 0.5wt% PVA fiber was added to the mortar to control cracks. A splitting crack test was performed on the cured sample to pre-create microcracks. Water was dripped onto the cracks to keep the inside of the cracks moist and water-rich. The self-healing effect was observed under a microscope after 7 days.

[0080] The self-healing mortar prepared using active cement particle microcapsules has good fluidity, high strength after setting and hardening, and a certain self-healing effect. It has a significant healing effect on microcracks smaller than 100μm and delays the complete passage of 5.0g of water through the crack by 150 seconds.

[0081] Example 9

[0082] A method for preparing self-healing mortar, comprising the following:

[0083] Step 1: Preparation of self-healing particles and microcapsules, the process is as follows:

[0084] 120.0g of cement (PC 42.5), 30.0g of UEA concrete expansion agent (Wuhan Ounce Manpen Building Materials Co., Ltd.), 0.6g of sodium gluconate, and 15.0g of PVP ethanol solution (20.0wt%) were uniformly mixed and pressed into shape under a pressure of 200.0kN. After adsorbing PEG8000, the mixture was crushed and screened to obtain active cement particles with a particle size of 600-900μm. A 25.0wt% m-phenylenediamine-ethanol solution was sprayed onto the surface of the active cement particles, and the particles were dried to obtain the final active cement particles.

[0085] 10.0g of activated cement particles, 8.0g of tristearate, 10.8g of IPDI, 1.2g of Suprasec 2644, and 0.75g of Span 85 were uniformly mixed to form the oil phase and heated to 85°C in a water bath. 9.0g of SDBS and 3.0g of TEPA were dissolved in 600mL of water and heated to 85°C in a water bath. The oil phase was then poured into the aqueous phase to uniformly disperse the particles, thus preparing activated cement particle microcapsules.

[0086] Step 2: Preparation of self-healing cement mortar:

[0087] Weigh 225g of water, 450g of cement, 90.0g of microcapsules, and 900g of sand, and add them to a mixing pot in the order of weighing. Mix thoroughly. Pour the fully mixed slurry into a mold, and demold after standard curing for 24 hours. The sample is then cured in water for 7 days. To test the self-healing effect of the self-healing mortar, 0.5wt% PVA fiber was added to the mortar to control cracking. A splitting crack test was performed on the cured sample to pre-create microcracks. The cracked sample was then immersed in water to undergo the self-healing process. The self-healing effect was observed under a microscope after 7 days.

[0088] The self-healing mortar prepared using active cement particle microcapsules has good fluidity, high strength after setting and hardening, and a certain self-healing effect. It has a significant healing effect on microcracks smaller than 150μm and delays the complete passage of 5.0g of water through the crack by 120 seconds.

Claims

1. A method for preparing a self-healing mortar using active cement particles microcapsules, characterized in that Includes the following steps: (1) Method for preparing and encapsulating active cement particles: Active cement powder and PVP ethanol solution are mixed, the mixture is compacted and then crushed and dried using a press; Active cement blocks are placed in liquid organic matter and vacuumed to allow the active cement blocks to adsorb liquid organic matter inside; Active cement blocks adsorbed with PEG are crushed into small particles; 25.0wt% m-phenylenediamine-ethanol solution is sprayed on the surface of the small particles, and the final active cement particles are obtained after drying; Active cement particles are encapsulated with polymers by a combination of interfacial polymerization and melt condensation. 10.0g active cement particles, 12.0g tristearate, 7.2g IPDI, 0.8g Suprasec 2644, 0.75g Span 85 and 0.75g toluene are uniformly mixed as the oil phase and heated to 75°C in a water bath; 9.0g SDBS and 3.0g TEPA are dissolved in 600mL of water and heated to 75°C in a water bath. The oil phase is poured into the aqueous phase to make the particles uniformly dispersed, and finally active cement particle microcapsules are prepared. (2) A method for preparing self-healing mortar using active cement particle microcapsules, which involves thoroughly mixing microcapsules, cement, sand and water; The active cement powder in step (1) is prepared according to the following mass ratio, with each part of active cement powder being 150.0g. The mass ratio of cement to expansive agent is between 9:1 and 6:4, and the amount of retarder added is between 0.15g and 4.5g. The cement used in the preparation of active cement particles is ordinary Portland cement. The expansive agent is bentonite or UEA concrete expansive agent. The retarder is one or more of sodium tripolyphosphate, citric acid, sodium gluconate, and boric acid. A PVP ethanol solution with a concentration between 5.0wt% and 50.0wt% is prepared. 0.6g to 60.0g of PVP ethanol solution is added to each part of active cement powder. The adsorbed organic matter is PEG of different molecular weights. The particle size of the crushed cement particles is between 100μm and 1250μm. In step (2), when preparing self-healing mortar, the water-cement ratio (i.e., the mass ratio of water to cement) is 0.3-0.7, the sand ratio (i.e., the mass ratio of cement to sand) is between 1:1 and 1:5, and the microcapsule dosage is 0.1%-10.0% of the total mass of the self-healing mortar.

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